Technical Abstract:
Pathogenic microbes such as Escherichia coli O157:H7, Salmonella serovars, and Listeria monocytogenes have been reported on fruits and leafy greens and represent enormous food safety risks. Biocontrol, physical and chemical measures are used to reduce and inactivate microbial contamination on produce. In this research, we investigated the efficacy of biocontrol on fruits, leafy greens, and in broths. Pathogenic microbes were inoculated at 4 log cfu/g and the biocontrol applied at 6 log cfu/g or ml. In experiments on the efficacy of biocontrol of Salmonella serovars (Typhimurium, Poona, Montevideo) by Pseudomonas spp., reductions of Salmonella ranged from 0.29-1.47 log cfu/ml. Similarly, reductions of E. coli O157:H7 with P. fluorescens on spinach ranged from 0.5-2.1 log cfu/g. Biocontrol efficacy was significantly (P<0.05) impacted by storage temperatures and time as optimum reductions were observed at 15 deg C (1.5-2.4 log cfu/g). When P. chlororaphis and P. fluorescens were co-inoculated with Salmonella serovars, their biocontrol efficacies were similar. Assessment of Bacteriovorax spp. on E. coli O157:H7 and Salmonella serovars demonstrated predation of these foodborne pathogens with Bacteriovorax spp. implying great potential for biocontrol of pathogenic bacteria on produce. It appears that concurrent use of multiple biocontrol (non-pathogenic) microbes and combinations of measures may greatly enhance their efficacies on foodborne pathogens.